scholarly journals Molecular-level insights into the electronic effects in platinum-catalyzed carbon monoxide oxidation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenyao Chen ◽  
Junbo Cao ◽  
Jia Yang ◽  
Yueqiang Cao ◽  
Hao Zhang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Steady State ◽  
Density Functional ◽  
Molecular Level ◽  
Structural Parameters ◽  
Catalyst Design ◽  
Grand Challenge ◽  
Support Surface ◽  
Dissociation Pathway ◽  
Electronic Effects

AbstractA molecular-level understanding of how the electronic structure of metal center tunes the catalytic behaviors remains a grand challenge in heterogeneous catalysis. Herein, we report an unconventional kinetics strategy for bridging the microscopic metal electronic structure and the macroscopic steady-state rate for CO oxidation over Pt catalysts. X-ray absorption and photoelectron spectroscopy as well as electron paramagnetic resonance investigations unambiguously reveal the tunable Pt electronic structures with well-designed carbon support surface chemistry. Diminishing the electron density of Pt consolidates the CO-assisted O2 dissociation pathway via the O*-O-C*-O intermediate directly observed by isotopic labeling studies and rationalized by density-functional theory calculations. A combined steady-state isotopic transient kinetic and in situ electronic analyses identifies Pt charge as the kinetics indicators by being closely related to the frequency factor, site coverage, and activation energy. Further incorporation of catalyst structural parameters yields a novel model for quantifying the electronic effects and predicting the catalytic performance. These could serve as a benchmark of catalyst design by a comprehensive kinetics study at the molecular level.

scholarly journals Modulating electronic structure of metal-organic frameworks by introducing atomically dispersed Ru for efficient hydrogen evolution

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yamei Sun ◽  
Ziqian Xue ◽  
Qinglin Liu ◽  
Yaling Jia ◽  
Yinle Li ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Density Functional ◽  
Metal Organic Frameworks ◽  
Catalyst Design ◽  
Single Atom ◽  
Hydrogen Energy ◽  
Structure Of Metal ◽  
Metal Organic

AbstractDeveloping high-performance electrocatalysts toward hydrogen evolution reaction is important for clean and sustainable hydrogen energy, yet still challenging. Herein, we report a single-atom strategy to construct excellent metal-organic frameworks (MOFs) hydrogen evolution reaction electrocatalyst (NiRu0.13-BDC) by introducing atomically dispersed Ru. Significantly, the obtained NiRu0.13-BDC exhibits outstanding hydrogen evolution activity in all pH, especially with a low overpotential of 36 mV at a current density of 10 mA cm−2 in 1 M phosphate buffered saline solution, which is comparable to commercial Pt/C. X-ray absorption fine structures and the density functional theory calculations reveal that introducing Ru single-atom can modulate electronic structure of metal center in the MOF, leading to the optimization of binding strength for H2O and H*, and the enhancement of HER performance. This work establishes single-atom strategy as an efficient approach to modulate electronic structure of MOFs for catalyst design.

Modulating Electronic Structure of Metal-Organic Frameworks by Introducing Atomically Dispersed Ru for Efficient Hydrogen Evolution

2020 ◽  
Author(s):  
Yamei Sun ◽  
Ziqian Xue ◽  
Qinglin Liu ◽  
Yaling Jia ◽  
Yinle Li ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Density Functional ◽  
Metal Organic Frameworks ◽  
Catalyst Design ◽  
Single Atom ◽  
Hydrogen Energy ◽  
Structure Of Metal ◽  
Metal Organic

Abstract Developing high-performance electrocatalysts toward hydrogen evolution reaction is important for clean and sustainable hydrogen energy, yet still challenging. Herein, we report a single-atom strategy to construct excellent metal-organic frameworks (MOFs) hydrogen evolution reaction (HER) electrocatalyst (NiRu0.13-BDC, BDC: terephthalic acid) by introducing atomically dispersed Ru. Significantly, the obtained NiRu0.13-BDC exhibits outstanding HER activity in all pH, especially with a low overpotential of only 36 mV at a current density of 10 mA cm-2 in 1 M phosphate buffered saline (PBS) solution, which is comparable to commercial Pt/C. X-ray absorption fine structures and the density functional theory calculations reveal that introducing Ru single-atom can modulate electronic structure of metal center in the MOF, leading to the optimization of binding strength for H2O and H*, and the enhancement of HER performance. This work establishes single-atom strategy as an efficient approach to modulate electronic structure of MOFs for catalyst design.

scholarly journals Dopants fixation of Ruthenium for boosting acidic oxygen evolution stability and activity

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Shaoyun Hao ◽  
Min Liu ◽  
Junjie Pan ◽  
Xiangnan Liu ◽  
Xiaoli Tan ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Oxygen Evolution ◽  
Density Functional ◽  
Polymer Electrolyte Membrane ◽  
Density Functional Theory Calculations ◽  
Grand Challenge ◽  
Oxygen Intermediates ◽  
Co Doping ◽  
Electrolyte Membrane ◽  
Acidic Electrolyte

Abstract Designing highly durable and active electrocatalysts applied in polymer electrolyte membrane (PEM) electrolyzer for the oxygen evolution reaction remains a grand challenge due to the high dissolution of catalysts in acidic electrolyte. Hindering formation of oxygen vacancies by tuning the electronic structure of catalysts to improve the durability and activity in acidic electrolyte was theoretically effective but rarely reported. Herein we demonstrated rationally tuning electronic structure of RuO2 with introducing W and Er, which significantly increased oxygen vacancy formation energy. The representative W0.2Er0.1Ru0.7O2-δ required a super-low overpotential of 168 mV (10 mA cm−2) accompanied with a record stability of 500 h in acidic electrolyte. More remarkably, it could operate steadily for 120 h (100 mA cm−2) in PEM device. Density functional theory calculations revealed co-doping of W and Er tuned electronic structure of RuO2 by charge redistribution, which significantly prohibited formation of soluble Rux>4 and lowered adsorption energies for oxygen intermediates.

First-Principles Study on Electronic Structure, Elasticity, Debye Temperature and Anisotropy of Cubic KCaF3

2020 ◽  
Vol 999 ◽  
pp. 109-116
Author(s):  
Xing Liu ◽  
Jia Fu ◽  
Man Man Han ◽  
Kai Xin Sun ◽  
Sheng Li Wei
Keyword(s):  
Electronic Structure ◽  
Debye Temperature ◽  
First Principles ◽  
Density Functional ◽  
Elastic Moduli ◽  
Poisson Ratio ◽  
Structural Parameters ◽  
Functional Material ◽  
Covalent Bonds ◽  
Functional Theory

As a potential functional material in the perovskite family, the KCaF3 on electronic structure, elasticity, Debye temperature and anisotropy are studied based on density functional theory (DFT). Above all, the structural parameters of KCaF3 crystal are optimized. Then the elastic constants and Debye temperature are calculated. The results show that: (1) KCaF3 is composed of covalent bonds, in which the Ca-F bond is stronger than K-F. (2) Ca atom mainly contributes for the electronic properties of KCaF3. (3) The structural parameters of KCaF3 is in fair agreement with the experimental data. (4) The anisotropy of KCaF3 was analyzed from the pure and quasi waves, of which the longitudinal wave velocity in the direction of [100] is the larger than the others two directions ([110] and [111]). Finally, The homogenized elastic moduli (bulk modulus B, shear modulus G, Young's modulus E), Pugh and Poisson ratio, are obtained. This research is meaningful and thus to provides a good theoretical guidance for the design the new ABX3-type material with better performance.

Theoretical investigation of dielectric properties of rare earth stillwellite compounds

2015 ◽  
Vol 29 (21) ◽  
pp. 1550154
Author(s):  
R. Shaltaf ◽  
J. Khalifeh
Keyword(s):  
Electronic Structure ◽  
Rare Earth ◽  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Density Functional ◽  
Structural Parameters ◽  
The Other ◽  
Static Dielectric Permittivity ◽  
Dielectric Tensors

Ab initio density functional calculations are performed to investigate the dielectric properties of LnBSiO 5 (Ln = Ce, Pr, Nd) with the stillwellite structure. The calculated structural parameters are found to agree well with existing experimental results. The three compounds possess insulating electronic structure with nearly isotropic high frequency dielectric permittivity tensors. On the other hand, the static dielectric permittivity tensors are found to be less isotropic. The anisotropy of static dielectric tensors are found to increase as the atomic number of the lanthanide increases.

scholarly journals SEPARAÇÃO ENANTIOSSELETIVA DA OXIBUTININA: UMA INVESTIGAÇÃO TEÓRICA E EXPERIMENTAL

Química Nova ◽  
2021 ◽  
Author(s):  
Lilian Zin ◽  
Camilla Silva ◽  
Luciana Guimarães ◽  
Keyller Borges ◽  
Clebio Nascimento
Keyword(s):  
High Performance ◽  
Density Functional ◽  
Molecular Level ◽  
Structural Parameters ◽  
Density Functional Theory Calculations ◽  
Normal Phase ◽  
Chiral Discrimination ◽  
Enantioselective Separation ◽  
Functional Theory ◽  
Diastereomeric Complexes

ENANTIOSELECTIVE SEPARATION OF OXYBUTYNIN: A THEORETICAL AND EXPERIMENTAL INVESTIGATION. In this work, we have studied both experimentally and theoretically the oxybutynin chiral discrimination. According to the main results, the enantioseparation of oxybutynin was efficiently achieved by high performance liquid chromatography in normal phase using the Chiralpak® AD column, which has amylose tris (3,5‐dimethylphenylcarbamate) as a chiral selector. The energetic and structural parameters obtained via density functional theory calculations pointed out the chiral discrimination as well as the enantiomeric elution order of oxybutynin, thus explaining, at molecular level, the experimental data. Finally, the strength of the hydrogen bonds played a key role in the discrimination between the oxybutynin diastereomeric complexes formed.

scholarly journals First Insight on Electronic Structure, Structural Stability, Dynamical and Mechanical Properties of Two-Dimensional LaAuo3.

2019 ◽  
pp. 1-17
Keyword(s):  
Electronic Structure ◽  
Structural Stability ◽  
Density Functional ◽  
Structural Parameters ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Fundamental Understanding ◽  
Covalent Interactions ◽  
Detailed Chemical

Abstract The electronic structure, structural stability, dynamical, mechanical, ionic conductivity, optical properties, and bonding nature of LaAuO3 are investigated by means of first principle calculations based on density functional theory (DFT). The equilibrium structural parameters are obtained within the general gradient approximation (GGA), in particular using the Perdew Burke Ernzerhof (PBE) exchange correlation functional, while the electronic structure is investigated using the screened hybrid functional proposed by Heyd, Scuseria and Ernzerhof (HSE06). The computed band gaps values and the nature of the electronic structure are found to be similar to ZnO and GaN. The detailed chemical bonding analysis reveals the nature of bonds: La–O exhibit mainly ionic interaction, whereas Au-O exhibits iono-covalent interactions. This study provides a fundamental understanding of the structural, mechanical, and electronic properties of LaAuO3.

Doping effects on the geometric and electronic structure of tin clusters

2019 ◽  
Vol 21 (44) ◽  
pp. 24478-24488 ◽  
Author(s):  
Martin Gleditzsch ◽  
Marc Jäger ◽  
Lukáš F. Pašteka ◽  
Armin Shayeghi ◽  
Rolf Schäfer
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Beam Deflection ◽  
Functional Theory ◽  
Doping Effects ◽  
Depth Analysis ◽  
Trajectory Simulations

In depth analysis of doping effects on the geometric and electronic structure of tin clusters via electric beam deflection, numerical trajectory simulations and density functional theory.

Electronic Structure Benchmark Calculations of Inorganic and Biochemical Carboxylation Reactions

2018 ◽  
Author(s):  
Oscar A. Douglas-Gallardo ◽  
David A. Sáez ◽  
Stefan Vogt-Geisse ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Electronic Structure ◽  
Chemical Reactions ◽  
Density Functional ◽  
Correlation Energy ◽  
Electronic Energy ◽  
Basis Sets ◽  
Electronic Correlation ◽  
Correct Description ◽  
Carbon Dioxide Co2 ◽  
High Level

<div><div><div><p>Carboxylation reactions represent a very special class of chemical reactions that is characterized by the presence of a carbon dioxide (CO2) molecule as reactive species within its global chemical equation. These reactions work as fundamental gear to accomplish the CO2 fixation and thus to build up more complex molecules through different technological and biochemical processes. In this context, a correct description of the CO2 electronic structure turns out to be crucial to study the chemical and electronic properties associated with this kind of reactions. Here, a sys- tematic study of CO2 electronic structure and its contribution to different carboxylation reaction electronic energies has been carried out by means of several high-level ab-initio post-Hartree Fock (post-HF) and Density Functional Theory (DFT) calculations for a set of biochemistry and inorganic systems. We have found that for a correct description of the CO2 electronic correlation energy it is necessary to include post-CCSD(T) contributions (beyond the gold standard). These high-order excitations are required to properly describe the interactions of the four π-electrons as- sociated with the two degenerated π-molecular orbitals of the CO2 molecule. Likewise, our results show that in some reactions it is possible to obtain accurate reaction electronic energy values with computationally less demanding methods when the error in the electronic correlation energy com- pensates between reactants and products. Furthermore, the provided post-HF reference values allowed to validate different DFT exchange-correlation functionals combined with different basis sets for chemical reactions that are relevant in biochemical CO2 fixing enzymes.</p></div></div></div>

Towards a Design of Active Oxygen Evolution Catalysts: Insights from Automated Density Functional Theory Calculations and Machine Learning

2019 ◽  
Author(s):  
Seoin Back ◽  
Kevin Tran ◽  
Zachary Ulissi
Keyword(s):  
Machine Learning ◽  
Oxygen Evolution ◽  
Active Sites ◽  
Density Functional ◽  
Chemical Space ◽  
Density Functional Theory Calculations ◽  
Catalyst Design ◽  
Transition Metal Catalysts ◽  
Oxide Materials ◽  
Design Strategies

<div> <div> <div> <div><p>Developing active and stable oxygen evolution catalysts is a key to enabling various future energy technologies and the state-of-the-art catalyst is Ir-containing oxide materials. Understanding oxygen chemistry on oxide materials is significantly more complicated than studying transition metal catalysts for two reasons: the most stable surface coverage under reaction conditions is extremely important but difficult to understand without many detailed calculations, and there are many possible active sites and configurations on O* or OH* covered surfaces. We have developed an automated and high-throughput approach to solve this problem and predict OER overpotentials for arbitrary oxide surfaces. We demonstrate this for a number of previously-unstudied IrO2 and IrO3 polymorphs and their facets. We discovered that low index surfaces of IrO2 other than rutile (110) are more active than the most stable rutile (110), and we identified promising active sites of IrO2 and IrO3 that outperform rutile (110) by 0.2 V in theoretical overpotential. Based on findings from DFT calculations, we pro- vide catalyst design strategies to improve catalytic activity of Ir based catalysts and demonstrate a machine learning model capable of predicting surface coverages and site activity. This work highlights the importance of investigating unexplored chemical space to design promising catalysts.<br></p></div></div></div></div><div><div><div> </div> </div> </div>

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